What is it?
This is a method for individually extracting the relative preferences of a set of criteria or aspects. It was designed for its application in outranking multicriteria decision aiding methods, however it has been found useful to discover underlying and sometimes conflicting reasons for those preferences in a participatory process.

What is needed?The application of the method requires:- a set of cards with the name, description (or representative image in the case of stakeholders who cannot read) of each criterion in evaluation.- a set of blank cards (at least 5 more times as the number of criterion).- a log document to immediately write down the final cards’ arrangement.- a photographic camera to take a photo of the final cards’ arrangement.- a notebook to write down the conversations and explanations for the arrangement.

After explaining the procedure, the completion of the process may take 10-20 minutes. No essential skills are necessary. Although in some context more explanation and examples will be necessary, especially if the criterion may not be easy to grasp by non-experts.

Is an expert needed?
No, no expert needed The procedure and calculations are very simple and can be prepared in an excel spreadsheet to be analyzed after the process.

How toImplementation:1. Explain the meaning of each previously selected set of criteria and the objective of the process.2. Give the set of cards with the criterion to the participants in no specific order. Asked the participants to arrange them from the one that is the least important on their left, to the one that is the most important on their far right. If two or more criteria are considered equally important, they can be arranged in a group.3. Asked them to use the blank cards to express if the difference between two criterion or group of criteria is different to the previous, as if they were steps in a staircase: is the difference always the same, or there are groups more separated from the rest?4. Once they have finished the arrangement asked them to explain their reasons for the different groups.5. Finally asked them to tell you how much more important is the most important criterion/group of criteria on their far right, compared to the least important ones: they are two times more important, three times, ten times? This is called the Z-ration that will be used to determine the absolute value of each participant evaluation scale.

Data capture:Once the arrangement and Z-ration has been given, take a photo and write down the number and names of the criteria in each set from the left to the right, the blank cards used between groups of cards and the Z-ration for the participant.

Data analysis:To obtain the weight of each group of criteria and each criterion in the set you will need to use the number of cards per set, the blank cards and the Z ration. The calculation is a normalization of the Z-ration in terms of the criteria set. A detail of the calculations can be found in Figueira and Roy 2002. It is recommended to have the calculations prepared in advance in an excel spreadsheet. See an example of this spreadsheet in http://practice-netweb.eu/sites/default/files/D2_3_PRACTICE_IAPro.pdf (page 58).

Good practice tips-It is important to find different and simple ways of describing each criterion without influencing the participants’ evaluations. If images are necessary, it is also important to be as neutral as possible. Avoid giving positive or negative connotations in your explanations.-Another aspect that has been found more difficult to explain is the meaning of the Z-ration. Giving examples of what this difference may be (e.g. double of importance, ten times more important), could avoid the use of disproportionate quantities.-It is useful to identify each criterion with a code to capture the results faster than having to write down the complete name.-Use different cards colors for the criterion and the blank cards.

Success storiesThis process has been applied to a variety of stakeholders in the context of an international project called PRACTICE. A version of the method applied in this context is described in the IAPro guideline (page 47): http://practice-netweb.eu/sites/default/files/D2_3_PRACTICE_IAPro.pdf

An application showing further possibilities of the method can be found in:

To learn moreThe reference to the original method and calculations in:Figueira, J., and B. Roy. 2002. Determining the weights of criteria in the ELECTRE typemethods with a revised Simos’ procedure. European Journal of Operational Research139:317–26. doi:10.1016=S0377-2217(01)00370-8